U.S. patent number 11,236,003 [Application Number 16/757,078] was granted by the patent office on 2022-02-01 for methods for controlling separation between glasses during co-sagging to reduce final shape mismatch therebetween.
This patent grant is currently assigned to Corning Incorporated. The grantee listed for this patent is CORNING INCORPORATED. Invention is credited to Steven Roy Burdette, Anurag Jain, Stephane Poissy, Zheming Zheng.
United States Patent |
11,236,003 |
Burdette , et al. |
February 1, 2022 |
Methods for controlling separation between glasses during
co-sagging to reduce final shape mismatch therebetween
Abstract
Embodiments of the disclosure relate to a method of controlling
the flow of fluid, such as air, between a stack of glass sheets
during a co-sagging process. In embodiments, this involves a
particular method and certain mechanical means of applying force at
or near the edges and/or corners of a stack of glass sheets during
a co-sagging process. In other embodiments, this involves creating
low pressure regions at or near the edges and/or corners during the
co-sagging process. In particular, controlling the flow of fluid
between glass sheets is particularly suitable for preventing shape
mismatch between two glass sheets having different thicknesses
and/or compositions.
Inventors: |
Burdette; Steven Roy (Big
Flats, NY), Jain; Anurag (Painted Post, NY), Poissy;
Stephane (Brunoy, FR), Zheng; Zheming
(Horseheads, NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING INCORPORATED |
Corning |
NY |
US |
|
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Assignee: |
Corning Incorporated (Corning,
NY)
|
Family
ID: |
1000006086669 |
Appl.
No.: |
16/757,078 |
Filed: |
October 16, 2018 |
PCT
Filed: |
October 16, 2018 |
PCT No.: |
PCT/US2018/056107 |
371(c)(1),(2),(4) Date: |
April 17, 2020 |
PCT
Pub. No.: |
WO2019/079315 |
PCT
Pub. Date: |
April 25, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200262733 A1 |
Aug 20, 2020 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62736791 |
Sep 26, 2018 |
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62574082 |
Oct 18, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03B
23/027 (20130101); C03B 23/0352 (20130101) |
Current International
Class: |
C03B
23/035 (20060101); C03B 23/025 (20060101); C03B
23/027 (20060101) |
References Cited
[Referenced By]
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Other References
International Search Report and Written Opinion of the
International Searching Authority; PCT/US2018/056107; dated Jan.
23, 2019; 14 Pages; European Patent Office. cited by applicant
.
Linnhofer et al. "Lightweight conventional automotive glazing",
IBEC '97, Automotive Glass and Glazing, 1997. pp. 25-27. cited by
applicant .
Linnhofer et al. "Resistance of glazings to stone impact",
Autotest'96, Jul. 1996. 4 pgs. cited by applicant .
Shetty, "Failure probability of laminated architectural glazing due
to combined loading of wind and debris impact", Engineering Failure
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applicant.
|
Primary Examiner: Szewczyk; Cynthia
Attorney, Agent or Firm: Riggs; Frank B. Johnson; William
M.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national stage application under 35 U.S.C.
.sctn. 371 of International Application No. PCT/US2018/056107,
filed on Oct. 16, 2018, which claims the benefit of priority under
35 U.S.C. .sctn. 119 of U.S. Provisional Application Ser. No.
62/736,791 filed on Sep. 26, 2018, and U.S. Provisional Application
Ser. No. 62/574,082 filed on Oct. 18, 2017, the content of each are
relied upon and incorporated herein by reference in their entirety.
Claims
What is claimed is:
1. A process for co-forming a stack of glass sheets to have similar
curvatures, the process comprising: placing a first sheet of glass
material on a support surface of a shaping frame, the shaping frame
defining an open central cavity surrounded at least in part by the
support surface; placing a second sheet of glass material over the
first sheet of glass material, wherein the first sheet of glass
material and the second sheet of glass material are both supported
by the shaping frame; heating the first sheet of glass material and
the second sheet of glass material together while supported by the
shaping frame such that central regions of the first and second
sheets of glass material deform downward into the open central
cavity of the shaping frame; and during at least a portion of the
heating, controlling a flow of fluid in a space between the first
sheet of glass material and the second sheet of glass material at
or near one or more of the edges and/or corners of the first and
second sheets of glass material, wherein the first sheet of glass
material comprises a first outer surface and a first inner surface
opposite the first outer surface, and the second sheet of glass
material comprises a second outer surface and a second inner
surface opposite the second outer surface, the first inner surface
facing the second inner surface when the first sheet of glass
material and the second sheet of glass material are both supported
by the shaping frame.
2. The process of claim 1, wherein the controlling the flow of the
fluid into the space comprises minimizing separation of the first
sheet of glass material and the second sheet of glass material at
or near one or more of the edges and/or corners.
3. The process of claim 1, wherein the controlling the flow of the
fluid into the space comprises creating a low pressure region at or
near one or more of the edges and/or corners of the first and
second sheets of glass material.
4. The process of claim 3, wherein controlling the flow of fluid
into the space comprises flowing a fluid under pressure at or near
one or more of the edges and/or corners of the first and second
sheets of glass material to create the low pressure region.
5. The process of claim 1, wherein controlling the flow of the
fluid into the space comprises applying a force at or near one or
more of the edges and/or corners or over a surface of the first
sheet of glass material and of the second sheet of glass
material.
6. The process of claim 5, wherein the force is applied via a clip
placed in contact with the first and second sheets of glass
material.
7. The process of claim 6, wherein the clip comprises: an elongated
body having an open-ended cross-section; a first clamping surface
adapted to contact a lower surface of the first sheet of glass
material; and a second clamping surface adapted to contact an upper
surface of the second sheet of glass material.
8. The process of claim 7, wherein the elongated body comprises a
tubular body have a C-shaped cross-section.
9. The process of claim 7, wherein the clip further comprises an
abutment edge adapted at one end of the open-ended cross-section,
the abutment edge adapted to contact an edge surface of the first
sheet of glass material.
10. The process of claim 5, wherein the force is applied via a
hanging weight structure.
11. The process of claim 10, wherein the hanging weight structure
comprises: a suspension body; an overhang projection that extends
from a first end of the suspension body over the second outer
surface of the second sheet of glass material; an armature
extending from a second end of the suspension body, wherein a
weight is suspended from the armature; and a contact surface
attached to the underside of the overhang protection, wherein the
contact surface contacts the second outer surface of the second
sheet of glass material.
12. The process of claim 5, wherein the force is applied via one or
more counterweights arranged at or near the edges and/or corners of
the first and second sheets of glass material.
13. The process of claim 5, wherein the force is applied via a
press that is lowered onto the second outer surface of the second
sheet of glass material.
14. The process of claim 5, wherein the force is applied via a
flexible weight.
15. The process of claim 14, wherein the flexible weight comprises
a metal cable.
16. The process of claim 14, wherein a fabric or layer comprising
at least one of copper, stainless steel, nickel, a ceramic, or
silver is provided between the flexible weight and the first glass
sheet and the second glass sheet.
17. The process of claim 1, wherein a layer of separation material
separates the first sheet of glass material from the second sheet
of glass material.
18. The process of claim 1, wherein the first sheet of glass
material has a first composition with a first viscosity during
heating that is different than a second viscosity of the second
sheet of glass material during heating, the second sheet of glass
material having a second glass composition.
19. The process of claim 1, wherein the first glass composition is
soda lime glass and the second glass composition is an alkali
aluminosilicate glass composition or an alkali aluminoborosilicate
glass composition.
20. The process of claim 1, wherein the first sheet of glass
material has an average thickness, T1, and the second sheet of
glass material has an average thickness, T2, wherein T1 is
different than T2.
Description
BACKGROUND
The disclosure relates generally to forming a curved glass laminate
article, and specifically to processes for co-forming (e.g.,
co-sagging) glass sheets while controlling separation of the glass
sheets to reduce shape mismatch.
Curved glass laminate sheets or articles find use in many
applications, including vehicle or automotive window glass.
Typically, curved glass sheets for such applications have been
formed from relatively thick sheets of glass material. To improve
shape consistency between individual glass layers of the laminate
article, the glass materials may be shaped to the desired
shape/curvature via a co-forming process, such as a co-sagging
process. Applicant has found that traditional co-sagging processes
may produce undesirable characteristics (e.g., shape mismatch) in
the curved glass sheets, the severity of which appears to increase
when the co-sagged pair of glass sheets have different thicknesses,
compositions, and/or viscosities.
SUMMARY
In one aspect, embodiments of a process for forming a stack of
glass sheets are provided. In the steps of the process, an outer
region of a first sheet of glass material is placed into contact
with a support surface of a shaping frame. The shaping frame
defines an open central cavity surrounded at least in part by the
support surface. Further, a second sheet of glass material is
placed over the first sheet of glass material. The first sheet of
glass material and the second sheet of glass material are both
supported by the shaping frame. Then, the flow of fluid in a space
between the first sheet of glass material and the second sheet of
glass material is controlled at or near one or more of the edges
and/or corners of the first and second sheets of glass material.
Next, the first sheet of glass material and the second sheet of
glass material are heated together while supported by the shaping
frame such that central regions of the first and second sheets of
glass material deform downward into the open central cavity of the
shaping frame.
In another aspect, embodiments of a method of forming a glass
laminate article are provided. The method includes a step of
placing an outer region of a first sheet of glass material into
contact with a support surface of a shaping frame. The shaping
frame defines an open central cavity surrounded at least in part by
the support surface. Then, a second sheet of glass material is
placed over the first sheet of glass material. Further, the first
sheet of glass material and the second sheet of glass material are
both supported by the shaping frame. The flow of fluid in a space
between the first sheet of glass material and the second sheet of
glass material is controlled at or near one or more of the edges
and/or corners of the first and second sheets of glass material.
Then, the first sheet of glass material and the second sheet of
glass material are heated together while supported by the shaping
frame such that central regions of the first and second sheets of
glass material deform downward into the open central cavity of the
shaping frame. Thereafter, the first sheet of glass material is
bonded to the second sheet of glass material.
An additional embodiment of the disclosure relates to a curved
glass laminate article including the first sheet of glass material
according to one of the described embodiments, the second sheet of
glass material according to one of the described embodiments, and a
polymer interlayer that binds the first sheet of glass material to
the second sheet of glass material.
Additional features and advantages will be set forth in the
detailed description that follows, and, in part, will be readily
apparent to those skilled in the art from the description or
recognized by practicing the embodiments as described in the
written description and claims hereof, as well as the appended
drawings.
It is to be understood that both the foregoing general description
and the following detailed description are merely exemplary, and
are intended to provide an overview or framework to understand the
nature and character of the claims.
The accompanying drawings are included to provide a further
understanding and are incorporated in and constitute a part of this
specification. The drawings illustrate one or more embodiment(s),
and together with the description serve to explain principles and
the operation of the various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, cross-sectional, exploded view showing
stacking of glass sheets for co-sagging, according to an exemplary
embodiment.
FIG. 2 is a schematic, cross-sectional view showing stacked glass
sheets supported on a bending ring, according to an exemplary
embodiment.
FIG. 3 is a cross-sectional view showing the stacked glass sheets
of FIG. 2 supported by a bending ring within a heating station,
according to an exemplary embodiment.
FIG. 4 is a detailed view of the stacked glass sheets of FIG. 2,
according to an exemplary embodiment
FIG. 5 depicts an embodiment of a clip for applying a force to a
stack of glass sheets, according to an exemplary embodiment.
FIG. 6 is a perspective view of a clip for applying a force to a
stack of glass sheets, according to an exemplary embodiment.
FIG. 7 is a schematic of a hanging weight system for applying a
force to a stack of glass sheets, according to an exemplary
embodiment.
FIG. 8 is a plan view of a glass preform cut from a glass sheet
used to form the stacked glass sheets of FIG. 2, according to an
exemplary embodiment.
FIG. 9 is a plan view of a vehicle having several glass windows
which could be formed of a laminate article produced from
co-sagging glass sheets according to an exemplary embodiment.
FIG. 10 is a simulation result for shape mismatch between two glass
sheets without a force applied at the edge/corner.
FIG. 11 is a temperature profile for the co-sagging simulation for
which results are depicted in FIGS. 10 and 12-15.
FIG. 12 is a simulation result for shape mismatch between two glass
sheets that have been clipped together during a simulated
co-sagging process, according to an exemplary embodiment.
FIG. 13 is a plan view of the simulation results of FIG. 12.
FIG. 14 is a simulation result for the pressure between stacked
glass sheets for which no force was applied at the edge/corner
during co-sagging.
FIG. 15 is a simulation result for the pressure between stacked
glass sheets for which clips were used to apply a force at the
corners during co-sagging, according to an exemplary
embodiment.
FIG. 16 illustrates the degree of sagging experienced by a thick
glass sheet within a heating station.
FIG. 17 illustrates the degree of sagging experienced by a thin
glass sheet within a heating station.
FIG. 18 depicts a side view of a fluid blowing system for
controlling the flow of fluid between two glass sheets during a
co-sagging process, according to an exemplary embodiment.
FIG. 19 depicts a perspective view of a fluid blowing system for
controlling the flow of fluid between two glass sheets during a
co-sagging process, according to an exemplary embodiment.
FIG. 20 depicts a flexible weighted ring placed over a stack of
glass sheets prior to co-sagging, according to an exemplary
embodiment.
FIG. 21 depicts the flexible weighted ring of FIG. 20 after the
stack of glass sheets has been co-sagged, according to an exemplary
embodiment.
FIG. 22 depicts a mounting ring and cable system configured to
secure the flexible weighted ring, according to an exemplary
embodiment.
FIG. 23 depicts an articulated bending ring usable with the
flexible weighted ring prior to co-sagging, according to an
exemplary embodiment.
FIG. 24 depicts the articulated bending ring of FIG. 23 after the
stack of glass sheets has been co-sagged, according to an exemplary
embodiment.
DETAILED DESCRIPTION
Embodiments of the disclosure relate to a method of controlling the
pressure or the flow of fluid, such as air, between a stack of
glass sheets during a co-sagging process. In embodiments, this
involves a particular method and certain mechanical means of
applying force at or near the edges and/or corners of a stack of
glass sheets during a co-sagging process. In other embodiments,
this involves creating low pressure regions at or near the edges
and/or corners during the co-sagging process. In particular,
controlling the pressure or the flow of fluid between glass sheets
is particularly suitable for preventing shape mismatch between two
glass sheets having different thicknesses, compositions, and/or
viscosities.
In certain embodiments, a force is applied via at least one of a
mechanical clip, a hanging weight structure, a plurality of
counterweights, a manually-operated or automated press, a flexible
weighted ring or layer, or the like. The force is sufficient to
reduce or eliminate edge or corner lifting of the upper glass sheet
from the lower glass sheet. Thus, a fluid film (e.g., an air film)
can be maintained between the sheets such that suction forces
between the sheets reduce shape mismatch of the glass sheets that
might otherwise be caused from fluid (e.g., air) being introduced
between the glass sheets due to edge or corner lifting of the upper
glass sheet from the lower glass sheet.
In other embodiments, high pressure fluid, such as air, is blown
towards the edges and/or corners of the glass sheets so as to lower
the pressure at the edges and/or corners of the glass sheets. The
lower pressure helps to seal the edges and/or corners to prevent a
loss of suction between the glass sheets.
As will be described more fully below, controlling the pressure or
the fluid flow between glass sheets during a co-sagging process
helps to limit edge/corner lifting and reduce shape mismatch. The
reduction in shape mismatch was confirmed via computer modeling and
experimentation.
In general, conventional processes for forming curved, laminated
glass articles involve heating a pair of stacked glass plates or
sheets on a forming ring to near the softening temperature of the
glass until the glass has sagged to the desired shape and depth. A
separation material can be used as a separation layer between the
two glass sheets preventing the glass sheets being bonded/fused
together during heating. While such co-sagging processes have a
variety of advantages (e.g., improving shape matching between the
glass sheets that will form the laminate, efficient use of heating
equipment, process throughput, etc.), co-sagging two different
glass materials can cause shape mismatches as a result of
differences in thickness, composition, viscosity, and,
consequently, sagging rates of the two glasses.
The shape mismatch between two glasses of different composition and
thickness is shown in FIGS. 16 and 17. As shown in FIG. 16, when a
sheet of glass is sagged under gravity by itself, a thicker glass
sheet 100 will produce a more parabolic shape. However, as shown in
FIG. 17, a thinner glass sheet 102 will produce a "bath tub" like
shape where curvature is greatest near the edges and is reduced
near the center. As a result, when the two sheets are co-sagged,
especially when the thinner sheet is on top of the thicker sheet,
the thinner sheet may pull up at or near the edges and corners of
the co-sagging sheets. As will be understood, the difference in sag
shape illustrated in FIGS. 16 and 17 generally will increase as the
thickness difference and the viscosity difference between the two
glass sheets increases, thereby increasing the shape mismatch
between the co-sagging sheets.
Applicant has found that a suction effect exists as a result of low
pressure created between glass sheets during the co-sagging
process. This suction effect is lost or reduced when edge lifting
allows fluid (typically air) to enter between the glass sheets. For
example, as described further below, a pressure gradient exists in
the space between two glass sheets during co-forming. At the edge
of the sheets, the pressure will be relatively large (i.e.,
atmospheric pressure or the pressure of the environment surrounding
the glass sheets), while the pressure will be relatively low near
the center of the glass sheets. As gravity drives the bending--and
separation--of the glass sheets during co-forming, the low pressure
in the internal region of the space between the glass sheets will
oppose separation of the glass sheets due to the suction effect.
Because the pressure at the edges of the glass sheets will
generally be at atmospheric pressure, a greater pressure gradient
between the edge of the glass sheets and the center of the glass
sheets will result in a lower pressure in this internal region, and
thus a greater suction effect. The closer the edges and/or corners
of the glass sheets are kept during co-forming, the slower the
speed at which fluid (e.g., air) can enter the internal region and
decrease this pressure gradient. In other words, the larger the
separation at the edges and/or corners of the glass sheets, the
faster the ambient fluid or air can penetrate the space between the
sheets and the faster the pressure gradient is diminished,
resulting in a diminished suction effect. Thus, embodiments of the
disclosure describe ways in which the flow of fluid into a space
between glass sheets can be controlled so as to maintain the
suction effect between the glass sheets. In one embodiment, the
flow of fluid between the glass sheets is controlled by applying a
force at or near one or more of the edges and/or corners of the
stack of glass sheets. For example, Applicant has found that a
relatively small force of, e.g., less than 1 N at locations where
corner lifting or edge lifting occurs, can prevent the loss of
suction between the glass sheets, which is thought to cause or
exacerbate shape mismatch. Applicant has developed multiple systems
that apply the requisite amount of force to address corner and edge
lifting while also reducing or eliminating shape mismatch between
the glass sheets. In other embodiment, the flow of fluid between
the glass sheets is controlled by blowing fluid toward the edges
and/or corners of the glass sheets so as to create low pressure
regions between the glass sheets at the edges and/or corners. These
low pressure regions help seal the edge and corners of the glass
sheets so that fluid does not flow between the sheets. In
embodiments, fluid is blown from under the lower glass sheet and/or
from above the upper glass sheet to create the low pressure
regions. Ultimately, each of the following means of controlling the
flow of fluid between the co-sagged glass sheets reduces the shape
mismatch of the final co-sagged glass sheets, even with large
differences in glass sheet thickness and glass sheet
viscosities.
Referring to FIG. 1 and FIG. 2, a system and process for forming a
curved glass article is shown according to an exemplary embodiment.
In general, system 10 includes one or more sheets of glass
material, shown as a pair of glass sheets 12 and 14, supported by a
shaping frame, shown as bending ring 16. It should be understood
that bending ring 16 may have a wide variety of shapes selected
based on the shape of the glass sheets to be supported, and use of
the term ring does not necessarily denote a circular shape.
As shown in FIG. 1, bending ring 16 includes a support wall, shown
as sidewall 20, and a bottom wall 22. Sidewall 20 extends upward
and away from bottom wall 22. The radially inward facing surface 24
of sidewall 20 defines an open central region or cavity 26, and an
upward facing surface of bottom wall 22 defines the lower end of
cavity 26. A radially outward facing surface 25 is opposite of
inward facing surface 24.
As shown in FIGS. 1 and 2, a separation material 18 is optionally
deposited between the lower glass sheet 12 and the upper glass
sheet 14. In general, separation material 18 is a material, such as
hexagonal boron nitride, graphite, molybdenum disulfide,
polytetrafluoroethylene, talc, calcium fluoride, cesium fluoride,
tungsten disulfide, etc., that helps prevent sheets 12 and 14 from
bonding together during the heating stages of the curve formation.
While the separation material 18 is depicted in FIGS. 1 and 2 as a
coherent layer, the separation material 18 can be, e.g., a powdered
ceramic layer, a slurry layer, a foam layer, etc. Further, the
separation material 18 can be sprayed, applied, or otherwise
deposited onto either a lower surface of the upper glass sheet 14
or an upper surface of the lower glass sheet 12. Thus, when the
upper glass sheet 14 is stacked over the lower glass sheet 12, the
lower surface of upper glass sheet 14 is in contact with separation
material 18, and the upper surface of the lower glass sheet 12 is
in contact with the separation material 18. As can be seen in FIGS.
1 and 2, in this arrangement, separation material 18 acts as a
barrier between glass layers 12 and 14 during the co-sagging
process.
To begin the co-sagging process, an outer region 28 of glass sheet
12 adjacent the outer perimeter edge 30 of the glass sheet is
placed into contact with a support surface, shown as upward facing
surface 32, of bending ring 16. In this arrangement, glass sheets
12 and 14 are both supported by the contact between upward facing
surface 32 with glass sheet 12 such that central regions 34 of
glass sheets 12 and 14 are supported over central cavity 26. In the
embodiment depicted, the flow of fluid between the glass sheets 12
and 14 is controlled via the application of a force 36 at or near
the edges and/or corners of the glass sheets 12 and 14. As will be
described more fully below, the force 36 can be applied a
mechanical clip, a weight, a press, or the like. However, as
mentioned above, the flow of fluid between the glass sheets 12 and
14 could additionally or alternatively be controlled by creating
low pressure regions at the edges and/or corners of the glass
sheets 12 and 14, and embodiments of this means of control are
provided later in the disclosure.
Next, referring to FIG. 3, bending ring 16, supported glass sheets
12 and 14 and separation material 18 are moved into a heating
station 40, such as an oven or serial indexing lehr. Within heating
station 40, glass sheets 12 and 14, separation material 18 and
bending ring 16 are heated (e.g., to near or at the softening
temperature of the glass material of glass sheets 12 and 14) while
glass sheets 12 and 14 are supported on bending ring 16. As glass
sheets 12 and 14 are heated, a shaping force, such as the downward
force 42, causes central region 34 of glass sheets 12 and 14 to
deform or sag downward into central cavity 26 of bending ring 16.
The force 36 prevents the edges of the upper glass sheet 14 from
pulling away from the lower glass sheet 12 during the co-sagging
process.
In specific embodiments, the downward force 42 is provided by
gravity. In some embodiments, the downward force 42 may be provided
via air pressure (e.g., creating a vacuum on the convex side of
glass sheets 12 and 14, blowing air on the concave side of glass
sheets 14, via press) or through a contact-based molding machine.
Regardless of the source of the deforming force 42, this procedure
results in glass sheets 12 and 14 having a curved shape as shown in
FIG. 3.
After a period of time determined to allow glass sheets 12 and 14
to develop the desired curved shape, bending ring 16 along with the
supported glass sheets 12 and/or 14 are then cooled to room
temperature. Thus, the shaped, deformed or curved glass sheets 12
and 14 are allowed to cool, fixing glass sheets 12 and 14 into the
curved shape created within heating station 40. Once cooled, curved
glass sheets 12 and 14 are removed from bending ring 16 and another
set of flat glass sheets are placed onto bending ring 16, and the
shaping process is repeated. Following shaping, the now curved
glass sheets 12 and 14 are bonded together (e.g., typically via a
polymer interlayer) into the final curved glass, laminate
article.
In particular embodiments, glass sheets 12 and 14 may be
particularly susceptible to edge and/or corner separation as a
result of large thickness differences and/or material differences
(e.g., viscosities) between glass sheets 12 and 14. Referring to
FIG. 4, in specific embodiments, the force 36 enables co-sagging of
glass sheets 12 and 14 with reduced edge and corner separation even
where a large thickness or viscosity differential exists between
the glass sheets 12 and 14. As shown in FIG. 4, glass sheet 12 has
a thickness, shown as T1, and glass sheet 14 has a thickness, shown
as T2. In embodiments, T1 is different from T2, and specifically T1
is greater than T2. In various embodiments, T1 is at least 2.5
times greater than T2, and in other embodiments, T2 is at least 2.5
times greater than T1. In specific embodiments, T1 is between 1.5
mm and 4 mm, and T2 is between 0.3 mm and 1 mm, and in even more
specific embodiments, T2 is 0.7 mm or less, or is less than 0.6 mm.
In specific embodiments: T1 is 1.6 mm and T2 is 0.55 mm; T1 is 2.1
mm and T2 is 0.55 mm; T1 is 2.1 mm and T2 is 0.7 mm; T1 is 2.1 mm
and T2 is 0.5 mm; T1 is 2.5 mm and T2 is 0.7 mm. In the embodiment
shown in FIG. 4, the thicker glass sheet 12 is located below the
thinner glass sheet 14 when stacked on bending ring 16. However, it
should be understood that in other embodiments, the thinner glass
sheet 14 could instead be located below thicker glass sheet 12 in
the stack supported by bending ring 16.
It is believed that when glass sheets of different materials are
co-sagged together, viscosity differences between the two materials
at the co-sagging temperature results in edge and/or corner lifting
in the regions where sagging shape is different (see e.g., FIGS. 16
and 17). Applicant has determined that applying a force at edge
and/or corners of the glass sheets decreases or eliminates shape
mismatch when co-sagging glass sheets of different materials and/or
thicknesses.
Thus, in various embodiments, glass sheet 12 is formed from a first
glass material/composition, and glass sheet 14 is formed from a
second glass material/composition different from the first glass
material. In some such embodiments, the first glass material has a
viscosity that is different from the viscosity of the second glass
material during heating within heating station 40. While a wide
variety of glass materials may be used to form glass sheets 12
and/or 14, in specific embodiments, the first glass material of
sheet 12 is a soda lime glass, and the second glass material of
sheet 14 is an alkali aluminosilicate glass composition or an
alkali aluminoborosilicate glass composition. Additional exemplary
materials for glass sheets 12 and 14 are identified in detail
below.
Referring initially to the embodiment of controlling the flow of
fluid between the glass sheets 12 and 14 via application of a force
26, Applicant has determined that various means of applying a force
each allow for co-sagging glass sheets having different thicknesses
and/or different material properties while reducing or eliminating
shape mismatch between the glass sheets. Without wishing to be
bound by theory, Applicant's testing has indicated that the
clamping force decreases air flow between the glass sheets 12 and
14, allowing for better suction between glass sheets 12 and 14 such
that the glass sheets 12 and 14 are urged to remain together during
the co-sagging process. That is, being relatively thicker in size
and made of a lower viscosity material, the generally faster
sagging lower glass sheet 12 will pull the generally thinner and
more viscous upper glass sheet 14 into shape conformity throughout
the co-sagging process. In various embodiments described below, a
mechanical clip, a weight system, a hanging weight, and a press are
provided.
In FIG. 5, an embodiment of a clip 50 is provided. The clip 50
includes a tubular body 52 having a generally C-shaped
cross-section. At the lower end of the C-shaped cross-section of
the tubular body 52 is an abutment edge 54. Further below the
abutment edge 54 is a clamping surface 56, and at the upper end of
the C-shaped cross-section of the tubular body 52 is a clamping
curve 58. As can be seen in FIG. 5, the clip 50 is attached to the
stack of glass sheets 12 and 14 such that the clamping surface 56
is in contact with the lower surface of the lower glass sheet 12
and the clamping curve 58 is in contact with the upper surface of
the upper glass sheet 14. The clip 50 is pushed onto the stack of
glass sheets 12 and 14 until the abutment edge 54 contacts the
lower glass sheet 12.
The tubular body 52 of the clip 50 is shown in greater detail in
FIG. 6. The tubular body 52 has a length L. In embodiments, the
length L is from 5 mm to 50 mm. In another embodiment, the length L
is from 6 mm to 15 mm. However, embodiments are not limited to
particular lengths and can varied based on the particular use. It
is appreciated that, according to the methods discussed herein,
good shape matching between the glass sheets can be achieved even
with a clip that is small relative to the size of the glass sheets.
A distance D separates the clamping surface 56 and the clamping
curve 58. The distance D can be approximately the same as or less
than the thickness of the stack of glass sheets 12 and 14. In this
way, the distance D can increase when the clip 50 is attached to
the stack of glass sheets 12 and 14 and elastically deforms so as
to apply a spring clamping force between the clamping surface 56
and the clamping curve 58. In embodiments, the clamping force is 1
N or less over 6 mm. In another embodiment, the clamping force is
0.5 N or less over 6 mm, and in a particular embodiment, the
clamping force is 0.4 N over 6 mm. In another embodiment, the
clamping force is at least about 0.05 N over 6 mm. Further, because
the clip 50 is attached to the glass sheets 12 and 14 during the
co-sagging process, the clip 50 is able to withstand typical
co-sagging temperatures (e.g., 500.degree. C. to 650.degree. C.).
In an embodiment, the clip 50 is made from a high temperature
nickel-based, iron-based, or iron/nickel-based alloys, such as
Inconel 600 or Haynes 120, that maintain their spring stiffness at
co-sagging temperatures. Advantageously, the clip 50 as described
has low thermal mass such that clip 50 does not have a significant
thermal impact on the glass sheets 12 and 14.
In order to apply the force 36 via the clip 50, multiple clips 50
may be positioned around the perimeter of the stack of glass sheets
12 and 14. In an exemplary embodiment, two clips 50 are placed at
each corner of the stack of glass sheets 12 and 14. In particular,
according the plane of each sheet with an XY-coordinate plane, at
each corner the two clips are arranged substantially perpendicular
to each other such that one clip 50 is positioned on an edge of the
glass sheets 12 and 14 substantially parallel to the X-axis and the
other clip 50 is positioned on an edge of the glass sheets 12 and
14 substantially parallel to the Y-axis. Such an arrangement is
depicted in FIG. 13, which will be discussed more fully below.
In another embodiment shown in FIG. 7, the force 36 is applied via
a hanging weight structure 60. The hanging weight structure 60
includes a suspension body 62 with an overhang projection 64 that
extends over the upper glass sheet 14 and an armature 66 upon which
a weight 68 is suspended. In an aspect of this embodiment, a
flexible, V-shaped strip 70 is attached to the underside of the
overhang protection 64 such that the bottom of the V contacts the
upper surface of the upper glass sheet 14. Other shapes and/or
mechanisms can be substituted for the V-shaped strip 70 for the
purpose of contacting and applying the force 36 to the top surface
of glass sheet 14. The weight 68 pulls downwardly on the suspension
body 62 such that a clamping force 36 is applied to the glass
sheets 12 and 14 along the line of contact from the V-shaped strip
70. In particular, the glass sheets 12 and 14 are clamped between
the V-shaped strip 70 and the upper facing surface 32 of the
bending ring 16. In embodiments, the force provided by the hanging
weight structure 60 is from about 0.05 N to 1 N over 6 mm. In
another embodiment, the force is 0.5 N or less over 6 mm, and in a
particular embodiment, the force is 0.4 N over 6 mm. Further, in
embodiments, the length of the flexible V-shaped strip 70, i.e.,
the length of the line of contact, is from 5 mm to 50 mm. In
another embodiment, the length of the flexible V-shaped strip 70 is
from 6 mm to 12 mm.
In order to apply the force 36 via the hanging weight structure 60,
multiple hanging weight structures 60 can be utilized. For example,
the hanging weight structures 60 can be positioned as described
above with respect to the embodiments of the clip 50. Further, the
hanging weight structure 60 can be formed, for example, of the same
nickel-based, iron-based, or iron/nickel-based alloys as the clip
50, or just the flexible, V-shaped strip 70 can be made of the
nickel-based, iron-based, or iron/nickel-based alloys. In this way,
the thermal impact of the hanging weight structure(s) 60 on the
glass sheets 12 and 14 is minimized.
In still another embodiment, a plurality of counterweights is
arranged on the upper surface of the upper glass sheet 12. In an
embodiment, the counterweights are placed at the corners of the
glass sheets 12 and 14. In embodiments, the weights are from 2 lbs.
to 10 lbs., and in a specific embodiment, the weights are from 5
lbs. to 7 lbs. In another embodiment, a manually-operated or
automatic press lowers onto the stack of glass sheets 12 and 14 to
apply pressure at the corners and/or edges of the stack of the
glass sheets 12 and 14.
The force 36 as discussed in each of these previously described
embodiments is applied at or near one or more of the edges of the
stack of glass sheets 12 and 14 and/or at or near the one or more
of the corners of the stack of glass sheets 12 and 14. In
embodiments, at or near one of the corners and/or edges is within
20 mm of the edge and/or corner. In still another embodiment, at or
near one of the corners and/or edges is within 10 mm of the edge
and/or corner. In yet another embodiment, at or near one of the
corners and/or edges is within 5 mm of the edge and/or corner.
In still other embodiments shown in FIGS. 20-24, a flexible weight
110 is used to apply a force at edge(s) and/or corner(s) or over a
surface of the glass sheets 12, 14. As used herein, "flexible"
refers to the ability of the weight to conform to and/or remain in
contact with the surface of the glass sheets 12, 14 during forming
operations.
As depicted in FIG. 20, the glass sheets 12, 14 are arranged on the
bending ring 16 with the flexible weight 110 forming a ring at or
near at least one of the corners and/or edges of the glass sheets
12, 14. In embodiments, at or near one of the corners and/or edges
is within 20 mm of the edge and/or corner. In still another
embodiment, at or near one of the corners and/or edges is within 10
mm of the edge and/or corner. In yet another embodiment, at or near
one of the corners and/or edges is within 5 mm of the edge and/or
corner. In embodiments, the flexible weight 110 is placed along all
of the edges of the upper glass sheet 14, and in other embodiments,
the flexible weighted ring 110 is only placed along certain edges
of the upper glass sheet 14.
In other embodiments, the flexible weight 110 is a layer that
covers a surface of the glass sheets 12, 14. For example, in an
embodiment, the flexible weight 110 is a fabric that is placed over
the entire surface of the glass sheets 12, 14. That is, the
flexible weight 110 can be used to apply a force over the full
contour of the glass sheets 12, 14. Further, in embodiments, the
flexible weight 110 is used in conjunction with one or more of the
clip 50, hanging weight structure 60, or the counterweights
discussed above and/or in conjunction with the fluid blowing system
90 discussed below.
In embodiments, the flexible weight 110 is configured to apply a
force of at least about 0.05 N to 1 N over 6 mm. In another
embodiment, the flexible weight 110 is configured to apply a force
of at least about 0.1 N over 6 mm. In still another embodiment, the
force is 0.5 N or less over 6 mm, and in a particular embodiment,
the force is 0.4 N over 6 mm. In embodiments, the flexible weight
110 is made of a material that is able to withstand typical
co-sagging temperatures (e.g., 500.degree. C. to 650.degree. C.).
In embodiments, the material is at least one of stainless steel,
copper, nickel-based alloys (e.g., Inconel or Hastelloy), ceramic
materials, or a silver-coated copper material. In other
embodiments, the flexible weight 110 may be made of another
material, and a layer of stainless sell, copper, nickel-based
alloys, ceramic materials, or a silver-coated copper material is
placed between the flexible weight 110 and the surface of the glass
sheets 12, 14. In embodiments, the selection of the material for
the flexible weight 110 or to place between the flexible weight 110
and the glass sheets 12, 14 is based on selecting a material that
is non-reactive with glass and that will not stick to the glass
(e.g., by melt-bonding to the glass at typical co-sagging
temperatures).
Further, in embodiments wherein the flexible weight 110 is a ring,
the flexible weight 110 has a round cross-section. In such
embodiments, the flexible weight 110 is, for example, a cable, such
as a metal wire rope (e.g., 1.times.19 wire bundle, 7.times.7 wire
bundle, or 7.times.19 wire bundle). In another embodiment, the
flexible weight 110 has a flat cross section or an elongated cross
section. In such embodiments, the flexible weight 110 is, for
example, a metal or ceramic braided tube, hose, or sleeve or a
strip of metal fabric. In embodiments in which the flexible weight
110 is a braided metal or ceramic tube, hose, or sleeve, a weight
can be inserted into the tube, hose, or sleeve, or a series of
weights can be inserted along the length of the metal or ceramic
tube, hose, or sleeve.
Advantageously, using a flexible weight 110 of the material
described provides the benefit of avoiding the generation of
optical distortions on the surface of the glass sheets 12, 14. In
particular, the flexibility of the flexible weighted ring 110
avoids the formation of the optical distortions because the
flexible weight 110 moves with the glass sheets 12, 14 during
co-sagging.
Referring to FIG. 20, it can be seen that the bending ring 16
includes angled support surfaces 112. Prior to sagging, the lower
glass sheet 12 contacts a portion of the angled support surfaces
112. During sagging, the lower glass sheet 12 bends into conformity
with the angled support surfaces 112 to help define the curve,
resulting in the bent glass sheets 12, 14 as shown in FIG. 21. FIG.
21 also shows that the flexible weight 110 moves with glass sheets
12, 14 during sagging, continually providing a force at or near the
edges and/or corners of the glass sheets 12, 14. While not
depicted, the flexible weight 110 could also be a fabric or layer
that covers all or a portion of the surface of glass sheets 12, 14,
and the fabric or layer would also move with the glass sheets 12,
14 during sagging to continually provide a force over the surface
of the glass sheets 12, 14.
FIG. 22 provides another depiction of the flexible weight 110 in
which the flexible weight 110 is connected to a mounting ring 114
via cables 116. In embodiments, the mounting ring 114 is a
standalone device that is unconnected with the bending ring. In
other embodiments, the mounting ring 114 is connected to the
bending ring 16 as shown in FIG. 22. In the embodiment depicted,
the mounting ring 114 resides in a slot defined between two wall
portions 118. The two wall portions 118 extend upwardly from a
peripheral ledge 120 that is connected to the bending ring 16. In
embodiments, the peripheral ledge 120 and/or wall portions 118 may
extend around the entire bending ring 16, and in other embodiments,
the peripheral ledge 120 and/or wall portions 118 may extend only
intermittently around the bending ring 16.
The cables 116 are attached at a first end to the mounting ring 114
and at a second end to the flexible weight 110. The cables 116 can
be attached to the mounting ring 114 and flexible weighted ring 110
in a variety of suitable ways, including being looped around these
structures, being fastened to these structures, being clipped to
these structures, etc. In embodiments, the number of cables 116 may
be, e.g., at least two, at least one per side of the glass sheets
12, 14, at least one per corner of the glass sheets 12, 14, the
same number of cables 116 for each side of the glass sheets 12, 14,
or a different number of cables 116 on at least one side of the
glass sheets 12, 14. As with the flexible weight 110, the cables
116 are made of a material that is capable of withstanding typical
co-sagging temperatures. Further, in embodiments, the cables 116
are attached to the flexible weight 110 and to the mounting ring
114 in such a way that the cables 116 do not come into contact with
the glass sheets 12, 14 during co-sagging.
Advantageously, as shown in FIGS. 23 and 24, the flexible weight
110 is usable with an articulated bending ring 122. Referring to
FIG. 23, the articulated bending ring 122 includes a first curved
support member 124 and a second curved support member 126. The
first curved support member 124 is defined at least in part by a
first end face 128, a second end face 130, and a first curved
support surface 132 disposed therebetween. At the intersection of
the first end face 128 and the first curved support surface 132 is
a first corner 134, and at the intersection of the second end face
130 and the first curved support surface 132 is a second corner
136. Similarly, the second curved support member 126 is defined at
least in part by a third end face 138, a fourth end face 140, and a
second curved support surface 142 disposed therebetween. At the
intersection of the third end face 138 and the second curved
support surface 142 is a third corner 144, and at the intersection
of the fourth end face 140 and the second curved support surface
142 is a fourth corner 146. As shown in FIG. 23, the stack of glass
sheets 12, 14 is supported on the first corner 134 and the second
corner 136 of the first curved support member 124 and on the third
corner 144 and the fourth corner 146 of the second curved support
member 126 at the beginning and early stages of the co-sagging
process. FIG. 23 also demonstrates that the second corner 136 and
the fourth corner 146 connected via a hinge joint 148. Prior to
sagging, the first curved support member 124 and the second curved
support member 126 form somewhat of a W shape. That is, the first
curved support member 124 and the second curved support member 126
are arranged such that the first corner 134, the second corner 136,
the third corner 144, and the fourth corner 146 all have the same
maximum vertical position and are located in the same horizontal
plane. The first curved support surface 132 decreases in vertical
position and, after reaching a vertical minimum, transitions to
increasing in vertical position going from the first corner 134 to
the second corner 136. Similarly, the second curved support surface
142 decreases in vertical position and, after reaching a vertical
minimum, transitions to increasing in vertical position going from
the third corner 144 to the fourth corner 146. Thus, going from
left to right in FIG. 23, the articulated bending ring 122 begins
at a first vertical maximum at first corner 134, goes to a vertical
minimum at a point along the first curved support surface 132,
reaches a second vertical maximum at the second corner 136 and
fourth corner 146, goes to a second vertical minimum at a point
along the second curved support surface 142, and reaches a third
vertical maximum at the third corner 144, which is similar to the
shape of a W.
The first curved support member 124 is supported on a first roller
150, and the second curved support member 126 is supported on a
second roller 152. As the glass sheets 12, 14 begin to sag, the
weight of the glass sheets 12, 14 over the first curved support
surface 132 and the second curved support surface 126 cause second
corner 136 and the fourth corner 146 to drop down. Because of the
hinged connection between these corners 136, 146, which prevents
the corners 136, 146 from separating, the rollers 150, 152 instead
move apart, causing the first corner 134 and the third corner 144
to move upwardly (or in the opposite direction of the second corner
136 and the fourth corner 146). By the end of the sagging process
as shown in FIG. 24, the first curved support surface 132 and the
second curved support surface 142 define a continuous curve such
that the first curved support member 124 and the second curved
support member 126 transition from the W shape to a U shape in
which (going from left to right in FIG. 23) the first corner 134
and the third corner 134 are at vertical maximums, the second
corner 136 and the fourth corner 146 are at vertical minimums, the
first curved support surface 132 transitions from the vertical
maximum at the first corner 134 to the vertical minimum, and the
second curved support surface 142 transitions from the vertical
minimum to the vertical maximum at the third corner 144. In making
this transition, the flexible weight 110 is able to remain in
contact with the surface of the upper glass sheet 14, preventing
air pockets from forming between the glass sheets 12, 14.
Referring now to the embodiment of controlling the flow of fluid
between the glass sheets 12 and 14 via creation of low pressure
regions at the edges and/or corners of the glass sheets 12 and 14,
a fluid blowing system 90 is depicted in FIG. 18. The fluid blowing
system 90 creates low pressure regions 92 at the edges and/or
corners of the glass sheets 12 and 14 by directing high pressure
fluid (denoted by arrows 94) to the edge and/or corner regions. As
can be seen in FIG. 18, the fluid blowing system 90 can provide
high pressure fluid 94 both from above the upper glass sheet 14 and
from below the lower glass sheet 12. Alternatively, the fluid
blowing system 90 can provide high pressure fluid 94 from just one
of above the upper glass sheet 14 or below the lower glass sheet
12. As can also be seen in FIG. 18, the fluid blowing system 90 is
fed from a single fluid supply tank 96; however, the upper and
lower portions of the fluid blowing system 90 can be fed by
different fluid supply tanks 96 in other embodiments. Further,
multiple nozzles can be used to supply the high pressure fluid 94
to the edges and/or corners. For example, a nozzle can be provided
at each corner on one or both sides of the glass sheets 12 and 14.
Furthermore, the direction that the high pressure fluid 94 is made
to flow can be varied. In embodiments, the high pressure fluid 94
is directed substantially parallel to the nearest edge surface of
the glass sheets 12 and 14. In another embodiment, the high
pressure fluid 94 is made to flow in a direction substantially
parallel to the surface of one or both of the glass sheets 12 and
14.
Additionally, as can be seen in FIG. 19, the fluid blowing system
90 can direct the high pressure fluid 94 to the corners of the
stack of glass sheets 12 and 14. Such high pressure fluid 94 can
also be made to flow into the corners in a manner that is
substantially parallel to the upper surface of the upper glass
sheet 14 and/or substantially parallel to the lower surface of the
lower glass sheet 12. In particular, the fluid blowing system 90 is
used throughout the co-sagging process in certain embodiments.
However, in other embodiments, the fluid blowing system 90 can be
activated during only certain stages of the co-sagging process,
such as when deformation transitions from elastic to viscous flow
where edge-lifting and loss of suction may be more likely to
occur.
The fluid used in the fluid blowing system 90 can be any fluid that
is non-reactive with the glass materials at the co-sagging process
temperatures. In an embodiment, the fluid is air. In another
embodiment, the fluid is a relatively inert or noble gas or a
mixture of such gases. Exemplary fluids for use in the fluid supply
system include carbon dioxide, nitrogen, helium, argon, neon, and
the like.
The fluid blowing system 90 as described herein helps to maintain
the suction between the glass sheets 12 and 14. Without wishing to
be bound by theory, Applicant believes that, in accordance with
Bernoulli's principle, the fluid blowing system 90 creates low
pressure regions 92 at the corners and/or edges of the glass sheets
12 and 14 where edge-lifting is most prevalent. The lower pressure
at the corners seals the corners from the inrush of fluid that
might otherwise occur. In this way, suction between the glass
sheets 12 and 14 is maintained such that the shape mismatch between
the glass sheets 12 and 14 is reduced. The location, blowing
direction, and blowing force of the fluid blowing system 90 can be
arranged in various ways to create such low pressure regions 92 at
the desired locations of the glass sheets 12 and 14.
For completeness, additional steps for forming a glass laminate
article before and after the co-sagging process are provided.
Referring to FIG. 8, by way of example, glass sheet 12 or 14 (also
referred to as a preform) are cut from their individual stock glass
sheets 80. The shape of the perimeter 82 is defined by a flat
pattern as needed to produce the desired shape following
co-sagging. After glass sheets 12 and 14 are cut from the stock
glass sheet, the edges may be ground to break the sharp corners.
Following this process, glass sheets 12 and 14 are stacked and
co-sagged as explained above regarding FIGS. 1-4.
In various embodiments, a curved glass laminate article formed from
the process and/or system discussed herein is provided. In specific
embodiments, the curved glass laminate article includes sheets 12
and 14 bound together by an interlayer (e.g., a polymer interlayer
such as a polyvinyl butyral layer). In such embodiments, the glass
laminate article formed from glass sheets 12 and 14 is highly
asymmetrical (e.g., has the large thickness differences and/or
material property differences discussed above) while at the same
time having low levels of shape difference between the layers.
Referring to FIG. 9, use of glass laminate article made from the
glass sheets 12 and 14 as part of a vehicle window, roof or side
window, is shown. As shown, a vehicle 200 includes one or more side
windows 202, a roof 204, a back window 206 and/or a windshield 208.
In general, any of the embodiments of glass laminate article
discussed herein may be used for one or more side windows 202, a
roof 204, a back window 206 and/or a windshield 208. In general,
one or more side windows 202, a roof 204, a back window 206 and/or
a windshield 208 are supported within an opening defined by vehicle
frame or body 210 such that outer surface of glass layer 12 faces a
vehicle interior 212. In this arrangement, outer surface of glass
layer 14 faces toward the exterior of vehicle 200 and may define
the outermost surface of vehicle 200 at the location of the glass
article. As used herein, vehicle includes automobiles, rolling
stock, locomotive, boats, ships, airplanes, helicopters, drones,
space craft and the like. In other embodiments, glass laminate
article may be used in a variety of other applications where thin,
curved glass laminate articles may be advantageous, such as for
architectural glass, building glass, etc.
Glass sheets 12 and/or 14 can be formed from a variety of
materials. In specific embodiments, glass sheet 14 is formed from a
chemically strengthened alkali aluminosilicate glass composition or
an alkali aluminoborosilicate glass composition, and glass sheet 12
is formed from a soda lime glass (SLG) composition. In specific
embodiments, glass sheets 12 and/or 14 are formed from a chemically
strengthened material, such as an alkali aluminosilicate glass
material or an alkali aluminoborosilicate glass composition, having
a chemically strengthened compression layer having a depth of
compression (DOC) in a range from about 30 .mu.m to about 90 .mu.m,
and a compressive stress on at least one of the sheet's major
surfaces of between 300 MPa to 1000 MPa. In some embodiments, the
chemically strengthened glass is strengthened through ion
exchange.
Examples of Glass Materials and Properties
In various embodiments, glass sheets 12 and/or 14 may be formed
from any of a variety of strengthened glass compositions. Examples
of glasses that may be used for glass sheets 12 and/or 14 described
herein may include alkali aluminosilicate glass compositions or
alkali aluminoborosilicate glass compositions, though other glass
compositions are contemplated. Such glass compositions may be
characterized as ion exchangeable. As used herein, "ion
exchangeable" means that the layer comprising the composition is
capable of exchanging cations located at or near the surface of the
glass layer with cations of the same valence that are either larger
or smaller in size. In one exemplary embodiment, the glass
composition of glass sheets 12 and/or 14 comprises SiO.sub.2,
B.sub.2O.sub.3 and Na.sub.2O, where
(SiO.sub.2+B.sub.2O.sub.3).gtoreq.66 mol. %, and Na.sub.2O.gtoreq.9
mol. %. Suitable glass compositions for glass sheets 12 and/or 14,
in some embodiments, further comprise at least one of K.sub.2O,
MgO, and CaO. In a particular embodiment, the glass compositions
used in glass sheets 12 and/or 14 can comprise 61-75 mol. %
SiO.sub.2; 7-15 mol. % Al.sub.2O.sub.3; 0-12 mol. % B.sub.2O.sub.3;
9-21 mol. % Na.sub.2O; 0-4 mol. % K.sub.2O; 0-7 mol. % MgO; and 0-3
mol. % CaO.
A further example of glass composition suitable for glass sheets 12
and/or 14 comprises: 60-70 mol. % SiO.sub.2; 6-14 mol. %
Al.sub.2O.sub.3; 0-15 mol. % B.sub.2O.sub.3; 0-15 mol. % Li.sub.2O;
0-20 mol. % Na.sub.2O; 0-10 mol. % K.sub.2O; 0-8 mol. % MgO; 0-10
mol. % CaO; 0-5 mol. % ZrO.sub.2; 0-1 mol. % SnO.sub.2; 0-1 mol. %
CeO.sub.2; less than 50 ppm As.sub.2O.sub.3; and less than 50 ppm
Sb.sub.2O.sub.3; where 12 mol.
%.ltoreq.(Li.sub.2O+Na.sub.2O+K.sub.2O).ltoreq.20 mol. % and 0 mol.
%.ltoreq.(MgO+CaO).ltoreq.10 mol. %.
Even further, another example of glass composition suitable for
glass sheets 12 and/or 14 comprises: 63.5-66.5 mol. % SiO.sub.2;
8-12 mol. % Al.sub.2O.sub.3; 0-3 mol. % B.sub.2O.sub.3; 0-5 mol. %
Li.sub.2O; 8-18 mol. % Na.sub.2O; 0-5 mol. % K.sub.2O; 1-7 mol. %
MgO; 0-2.5 mol. % CaO; 0-3 mol. % ZrO.sub.2; 0.05-0.25 mol. %
SnO.sub.2; 0.05-0.5 mol. % CeO.sub.2; less than 50 ppm
As.sub.2O.sub.3; and less than 50 ppm Sb.sub.2O.sub.3; where 14
mol. %.ltoreq.(Li.sub.2O+Na.sub.2O+K.sub.2O).ltoreq.18 mol. % and 2
mol. %.ltoreq.(MgO+CaO).ltoreq.7 mol. %.
In a particular embodiment, an alkali aluminosilicate glass
composition suitable for glass sheets 12 and/or 14 comprises
alumina, at least one alkali metal and, in some embodiments,
greater than 50 mol. % SiO.sub.2, in other embodiments at least 58
mol. % SiO.sub.2, and in still other embodiments at least 60 mol. %
SiO.sub.2, wherein the ratio
((Al.sub.2O.sub.3+B.sub.2O.sub.3)/.SIGMA. modifiers)>1, where in
the ratio the components are expressed in mol. % and the modifiers
are alkali metal oxides. This glass composition, in particular
embodiments, comprises: 58-72 mol. % SiO.sub.2; 9-17 mol. %
Al.sub.2O.sub.3; 2-12 mol. % B.sub.2O.sub.3; 8-16 mol. % Na.sub.2O;
and 0-4 mol. % K.sub.2O, wherein the ratio
((Al.sub.2O.sub.3+B.sub.2O.sub.3)/.SIGMA.modifiers)>1.
In still another embodiment, glass sheets 12 and/or 14 may include
an alkali aluminosilicate glass composition comprising: 64-68 mol.
% SiO.sub.2; 12-16 mol. % Na.sub.2O; 8-12 mol. % Al.sub.2O.sub.3;
0-3 mol. % B.sub.2O.sub.3; 2-5 mol. % K.sub.2O; 4-6 mol. % MgO; and
0-5 mol. % CaO, wherein: 66 mol.
%.ltoreq.SiO.sub.2+B.sub.2O.sub.3+CaO.ltoreq.69 mol. %;
Na.sub.2O+K.sub.2O+B.sub.2O.sub.3+MgO+CaO+SrO>10 mol. %; 5 mol.
%.ltoreq.MgO+CaO+SrO.ltoreq.8 mol. %;
(Na.sub.2O+B.sub.2O.sub.3)--Al.sub.2O.sub.3.ltoreq.2 mol. %; 2 mol.
% Na.sub.2O--Al.sub.2O.sub.3.ltoreq.6 mol. %; and 4 mol.
%.ltoreq.(Na.sub.2O+K.sub.2O)--Al.sub.2O.sub.3.ltoreq.10 mol.
%.
In an alternative embodiment, glass sheets 12 and/or 14 may
comprise an alkali aluminosilicate glass composition comprising: 2
mol % or more of Al.sub.2O.sub.3 and/or ZrO.sub.2, or 4 mol % or
more of Al.sub.2O.sub.3 and/or ZrO.sub.2. In one or more
embodiments, glass sheets 12 and/or 14 comprise a glass composition
comprising SiO.sub.2 in an amount in the range from about 67 mol %
to about 80 mol %, Al.sub.2O.sub.3 in an amount in a range from
about 5 mol % to about 11 mol %, an amount of alkali metal oxides
(R.sub.2O) in an amount greater than about 5 mol % (e.g., in a
range from about 5 mol % to about 27 mol %). In one or more
embodiments, the amount of R.sub.2O comprises Li.sub.2O in an
amount in a range from about 0.25 mol % to about 4 mol %, and
K.sub.2O in an amount equal to or less than 3 mol %. In one or more
embodiments, the glass composition includes a non-zero amount of
MgO, and a non-zero amount of ZnO.
In other embodiments, glass sheets 12 and/or 14 are formed from a
composition that exhibits SiO.sub.2 in an amount in the range from
about 67 mol % to about 80 mol %, Al.sub.2O.sub.3 in an amount in
the range from about 5 mol % to about 11 mol %, an amount of alkali
metal oxides (R.sub.2O) in an amount greater than about 5 mol %
(e.g., in a range from about 5 mol % to about 27 mol %), wherein
the glass composition is substantially free of Li.sub.2O, and a
non-zero amount of MgO; and a non-zero amount of ZnO.
In other embodiments, glass sheets 12 and/or 14 are an
aluminosilicate glass article comprising: a glass composition
comprising SiO.sub.2 in an amount of about 67 mol % or greater; and
a sag temperature in a range from about 600.degree. C. to about
710.degree. C. In other embodiments, glass sheets 12 and/or 14 are
formed from an aluminosilicate glass article comprising: a glass
composition comprising SiO.sub.2 in an amount of about 68 mol % or
greater; and a sag temperature in a range from about 600.degree. C.
to about 710.degree. C. (as defined herein).
In some embodiments, glass sheets 12 and/or 14 are formed from
different glass materials from each other that differs in any one
or more of composition, thickness, strengthening level, and forming
method (e.g., float formed as opposed to fusion formed). In one or
more embodiments, glass sheets 12 and/or 14 described herein have a
sag temperature of about 710.degree. C., or less or about
700.degree. C. or less. In one or more embodiments, one of the
glass sheets 12 and 14 is a soda lime glass sheet, and the other of
the glass sheets 12 and 14 is any one of the non-soda lime glass
materials discussed herein. In one or more embodiments, glass
sheets 12 and/or 14 comprises a glass composition comprising
SiO.sub.2 in an amount in the range from about 68 mol % to about 80
mol %, Al.sub.2O.sub.3 in an amount in a range from about 7 mol %
to about 15 mol %, B.sub.2O.sub.3 in an amount in a range from
about 0.9 mol % to about 15 mol %; a non-zero amount of
P.sub.2O.sub.5 up to and including about 7.5 mol %, Li.sub.2O in an
amount in a range from about 0.5 mol % to about 12 mol %, and
Na.sub.2O in an amount in a range from about 6 mol % to about 15
mol %.
In some embodiments, the glass composition of glass sheets 12
and/or 14 may include an oxide that imparts a color or tint to the
glass articles. In some embodiments, the glass composition of glass
sheets 12 and/or 14 includes an oxide that prevents discoloration
of the glass article when the glass article is exposed to
ultraviolet radiation. Examples of such oxides include, without
limitation, oxides of: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, W, and
Mo.
Glass sheets 12 and/or 14 may have a refractive index in the range
from about 1.45 to about 1.55. As used herein, the refractive index
values are with respect to a wavelength of 550 nm. Glass sheets 12
and/or 14 may be characterized by the manner in which it is formed.
For instance, glass sheets 12 and/or 14 may be characterized as
float-formable (i.e., formed by a float process), down-drawable
and, in particular, fusion-formable or slot-drawable (i.e., formed
by a down draw process such as a fusion draw process or a slot draw
process). In one or more embodiments, glass sheets 12 and/or 14
described herein may exhibit an amorphous microstructure and may be
substantially free of crystals or crystallites. In other words, in
such embodiments, the glass articles exclude glass-ceramic
materials.
In one or more embodiments, glass sheets 12 and/or 14 exhibits an
average total solar transmittance of about 88% or less, over a
wavelength range from about 300 nm to about 2500 nm, when glass
sheets 12 and/or 14 has a thickness of 0.7 mm. For example, glass
sheets 12 and/or 14 exhibits an average total solar transmittance
in a range from about 60% to about 88%, from about 62% to about
88%, from about 64% to about 88%, from about 65% to about 88%, from
about 66% to about 88%, from about 68% to about 88%, from about 70%
to about 88%, from about 72% to about 88%, from about 60% to about
86%, from about 60% to about 85%, from about 60% to about 84%, from
about 60% to about 82%, from about 60% to about 80%, from about 60%
to about 78%, from about 60% to about 76%, from about 60% to about
75%, from about 60% to about 74%, or from about 60% to about
72%.
In one or more embodiments, glass sheets 12 and/or 14 exhibit an
average transmittance in the range from about 75% to about 85%, at
a thickness of 0.7 mm or 1 mm, over a wavelength range from about
380 nm to about 780 nm. In some embodiments, the average
transmittance at this thickness and over this wavelength range may
be in a range from about 75% to about 84%, from about 75% to about
83%, from about 75% to about 82%, from about 75% to about 81%, from
about 75% to about 80%, from about 76% to about 85%, from about 77%
to about 85%, from about 78% to about 85%, from about 79% to about
85%, or from about 80% to about 85%. In one or more embodiments,
glass sheets 12 and/or 14 exhibits T.sub.uv-380 or T.sub.uv-400 of
50% or less (e.g., 49% or less, 48% or less, 45% or less, 40% or
less, 30% or less, 25% or less, 23% or less, 20% or less, or 15% or
less), at a thickness of 0.7 mm or 1 mm, over a wavelength range
from about 300 nm to about 400 nm.
In one or more embodiments, glass sheets 12 and/or 14 may be
strengthened to include compressive stress that extends from a
surface to a depth of compression (DOC). The compressive stress
regions are balanced by a central portion exhibiting a tensile
stress. At the DOC, the stress crosses from a positive
(compressive) stress to a negative (tensile) stress.
In one or more embodiments, glass sheets 12 and/or 14 may be
strengthened mechanically by utilizing a mismatch of the
coefficient of thermal expansion between portions of the article to
create a compressive stress region and a central region exhibiting
a tensile stress. In some embodiments, the glass article may be
strengthened thermally by heating the glass to a temperature below
the glass transition point and then rapidly quenching.
In one or more embodiments, glass sheets 12 and/or 14 may be
chemically strengthening by ion exchange. In the ion exchange
process, ions at or near the surface of glass sheets 12 and/or 14
are replaced by--or exchanged with--larger ions having the same
valence or oxidation state. In those embodiments in which glass
sheets 12 and/or 14 comprises an alkali aluminosilicate glass, ions
in the surface layer of the article and the larger ions are
monovalent alkali metal cations, such as Li.sup.+, Na.sup.+,
K.sup.+, Rb.sup.+, and Cs.sup.+. Alternatively, monovalent cations
in the surface layer may be replaced with monovalent cations other
than alkali metal cations, such as Ag.sup.+, or the like. In such
embodiments, the monovalent ions (or cations) exchanged into glass
sheets 12 and/or 14 generate a stress.
Experimental Examples
Applicant has conducted a number of simulations and experiments to
understand and evaluate shape mismatch during co-sagging of high
asymmetry glass pairs as discussed herein.
During the experimental co-sagging process, two plates of glass of
different composition (and consequently different viscosities) were
initially stacked together with a layer of separation powder
between them. For the experiments, the thicker, lower sheet of
glass was soda lime glass (SLG), and the thinner, upper sheet is
alkali aluminosilicate glass (GG), in particular Gorilla Glass 2318
(available from Corning Incorporated, Corning, N.Y.). The size of
the separation powder particles was measured to be in the range of
10 .mu.m to 20 .mu.m, and thus, for the analyses performed, the
initial gap between the two glass sheets was assumed to be 10 .mu.m
to 20 .mu.m. Pressure P in the gap between two glasses sheets is
governed by Equation 1 below:
.differential..differential..gradient..times..times..mu..times..gradient.
##EQU00001## where, h is the gap between glass sheets as a function
of time t and .mu. is the air viscosity. This equation relates
pressure to gap opening and, generally, is valid as long as the
gap, h, is small. As long as the glass sheets are in an elastic
state, there is no gap change between the two glasses. At forming
temperatures when the viscosity of bottom SLG decreases to a point
that it will tend to sag away from harder GG at the top. However,
for separation of the glass sheets to occur, air must enter between
glass sheets, which typically happens from the edges.
Using computer analysis, the separation between SLG and GG glass
sheets, both without and with force applied to the edges and/or
corners, was simulated. The simulation result for a quarter of the
two stacked glass sheets 12 and 14 without clamping force is shown
in FIG. 10. In particular, for the simulation, the lower glass
sheet 12 was 2.1 mm SLG, and the upper glass sheet 14 was 0.55 mm
GG. Both glass sheets were 300 mm square. The separation between
the glass sheets 12 and 14 was set at 25 .mu.m and was not allowed
to decrease to less than 15 .mu.m. Further, as can be seen in FIG.
10, the glass sheets 12 and 14 are resting on the bending ring 16,
which for the purpose of simulation was 2 mm thick and 298 mm from
edge-to-edge in the X and Y directions. For the simulation, the
stacked glass sheets 12 and 14 were heated from 400.degree. C. to
625.degree. C. over 30 seconds, held for 60 seconds at that
temperature, and then cooled back to 400.degree. C. over 30
seconds. The temperature profile for the heating of the glass
sheets 12 and 14 is shown in FIG. 11. During the simulation, the
glass sheets 12 and 14 were allowed to sag under the force of
gravity.
Based on the color gradient in the legend, the edge and corner
regions of the glass sheets 12 and 14 lift upwardly after
treatment. Further, from the color gradient in the legend, the
centers of the glass sheets 12 and 14 both sag downwardly, but at
different amounts. In particular, the lower SLG glass sheet 12 sags
more than 0.6 mm lower than the upper GG glass sheet 14.
Specifically, the glass sheets 12 and 14 were separated by 0.675 mm
at the centers of the plates after 129 seconds. Without the effect
of the air film (i.e., the suction effect provided by the air
pressure in the separation between the sheets 12 and 14), the
separation would have been much greater, 15.168 mm, as found in a
separate simulation, indicating how much difference in viscosity
and thickness can create shape mismatch between glass sheets 12 and
14. Even the small mismatch of more than 0.6 mm can be too large
for certain applications, e.g., automotive windshields.
In FIGS. 12 and 13, the same simulation was performed with the
exception that the simulation included two clips 50 at each corner
of the stack of the glass sheets 12 and 14. For the simulation, the
clip 50 provided a clamping force of 0.4 N over a length of 6 mm.
The clips 50 were 12 mm long and 2 mm wide. As can be seen in FIGS.
12 and 13, the shape mismatch between the glass sheets 12 and 14
was much less than in the unclipped embodiment of FIG. 11. In
particular, the shape mismatch was 0.164 mm.
By comparing FIG. 10 to FIGS. 12 and 13, a source of the separation
can be determined. Specifically, the corner of the glass sheets 12
and 14 in FIG. 10 exhibits much greater edge/corner lift than the
corner of FIGS. 12 and 13. This separation is driven by mechanical
forces related to the bending of the sheets in the corner
(considering the differences in sagging between the sheets as shown
in FIGS. 16 and 17). The upper glass sheet 14 bends to a lesser
extent as a result of its higher viscosity, and a gap opens in the
corner. This gap allows air to enter between the glass sheets 12
and 14, reducing the effect of pressure between the plates.
FIGS. 14 and 15 depict the pressure between the glass sheets 12 and
14. FIG. 14 corresponds to the glass sheets 12 and 14 of FIG. 10
(i.e., no force 36 applied at the edges and/or corners), whereas
FIG. 15 corresponds to the glass sheets 12 and 14 of FIGS. 12 and
13 in which two clips 50 were attached at each corner. In FIG. 14,
the region of no suction (red color) is much larger than the region
of no suction in FIG. 15. Further, the clipped glass sheets 12 and
14 of FIG. 15 exhibited a greater suction pressure than the
unclipped glass sheets 12 and 14 of FIG. 14.
Further experimentation was performed in a static furnace with a
2.1 mm thick lower SLG sheet and 0.7 mm thick upper GG sheet. A
baseline experiment was performed in which no clips or weights were
positioned at the edges or corners of the glass sheets 12 and 14.
Thereafter, a force 36 was applied to the glass sheets 12 and 14
via a clip 50. Table 1 compares the shape mismatch in sag depths
for the two scenarios. A lower shape mismatch is observed in the
latter case in which clips 50 were used, indicating the
effectiveness of closing the gap created at the corners during
bending.
TABLE-US-00001 TABLE 1 Mismatch between SLG and GG during first
co-sagging trial Top and bottom Experiment Top glass Bottom glass
glass shape mismatch No clips 0.7 mm GG 2.1 mm SLG 3.3 mm Clipped
at corners 0.7 mm GG 2.1 mm SLG 1.7 mm
In another experiment, a baseline experiment was performed in which
no force was applied at the edges or corners of the glass sheets 12
and 14. Thereafter, an experiment was performed in which a
counterweight was placed at the corners of the glass sheets 12 and
14. Table 2 compares the measured shape mismatch between the two
scenarios. Again, a lower mismatch is achieved when using
counterweights.
TABLE-US-00002 TABLE 2 Mismatch between SLG and GG during second
co-sagging trial Top and bottom Experiment Top glass Bottom glass
glass shape mismatch No Counterweights 0.7 mm GG 2.1 mm SLG 1.8 mm
Counterweights at corners 0.7 mm GG 2.1 mm SLG 0.9 mm
Aspect 1 of this disclosure pertains to a process for co-forming a
stack of glass sheets to have similar curvatures, the process
comprising: placing a first sheet of glass material on a support
surface of a shaping frame, the shaping frame defining an open
central cavity surrounded at least in part by the support surface;
placing a second sheet of glass material over the first sheet of
glass material, wherein the first sheet of glass material and the
second sheet of glass material are both supported by the shaping
frame; heating the first sheet of glass material and the second
sheet of glass material together while supported by the shaping
frame such that central regions of the first and second sheets of
glass material deform downward into the open central cavity of the
shaping frame; and during at least a portion of the heating,
controlling a flow of fluid in a space between the first sheet of
glass material and the second sheet of glass material at or near
one or more of the edges and/or corners of the first and second
sheets of glass material, wherein the first sheet of glass material
comprises a first outer surface and a first inner surface opposite
the first outer surface, and the second sheet of glass material
comprises a second outer surface and a second inner surface
opposite the second outer surface, the first inner surface facing
the second inner surface when the first sheet of glass material and
the second sheet of glass material are both supported by the
shaping frame.
Aspect 2 of this disclosure pertains to the process of Aspect 1,
wherein the controlling the flow of the fluid into the space
comprises minimizing separation of the first sheet of glass
material and the second sheet of glass material at or near one or
more of the edges and/or corners.
Aspect 3 of this disclosure pertains to the process of Aspect 1 or
Aspect 2, wherein the controlling the flow of the fluid into the
space comprises creating a low pressure region at or near one or
more of the edges and/or corners of the first and second sheets of
glass material.
Aspect 4 of this disclosure pertains to the process of Aspect 3,
wherein controlling the flow of fluid into the space comprises
flowing a fluid under pressure at or near one or more of the edges
and/or corners of the first and second sheets of glass material to
create the low pressure region.
Aspect 5 of this disclosure pertains to the process of Aspect 4,
wherein the fluid that is flowing under pressure is flowing in a
direction substantially parallel to a nearest edge of the first and
second sheets of glass material.
Aspect 6 of this disclosure pertains to the process of Aspect 4,
wherein the fluid that is flowing under pressure is flowing in a
direction substantially parallel to a surface of the first sheet of
glass material or to a surface of the second sheet of glass
material.
Aspect 7 of this disclosure pertains to the process of any of
Aspects 4 to 6, wherein the fluid that is flowing under pressure is
flowing substantially parallel to at least a portion of the first
or second outer surface towards one or more of the edges and/or
corners of the first sheet of glass material or the second sheet of
glass material.
Aspect 8 of this disclosure pertains to the process of Aspect 1 or
Aspect 2, wherein controlling the flow of the fluid into the space
comprises applying a force at or near one or more of the edges
and/or corners or over a surface of the first sheet of glass
material and of the second sheet of glass material.
Aspect 9 of this disclosure pertains to the process of Aspect 8,
wherein the direction of the force is substantially perpendicular
to the second outer surface of the second sheet of glass
material.
Aspect 10 of this disclosure pertains to the process of Aspect 8,
wherein the force is from 0.1 N to 1 N
Aspect 11 of this disclosure pertains to the process of Aspect 10,
wherein the force is less than 0.5 N.
Aspect 12 of this disclosure pertains to the process of any of
Aspects 7 to 11, wherein the force is applied over a distance of 6
mm.
Aspect 13 of this disclosure pertains to the process of any of
Aspects 7 to 12, wherein the force is applied within 20 mm of an
edge of the first and second sheets of glass material.
Aspect 14 of this disclosure pertains to the process of any of
Aspects 7 to 13, wherein the force is applied via a clip placed in
contact with the first and second sheets of glass material.
Aspect 15 of this disclosure pertains to the process of Aspect 14,
wherein the clip comprises: an elongated body having an open-ended
cross-section; a first clamping surface adapted to contact a lower
surface of the first sheet of glass material; and a second clamping
surface adapted to contact an upper surface of the second sheet of
glass material.
Aspect 16 of this disclosure pertains to the process of Aspect 15,
wherein the elongated body comprises a tubular body have a C-shaped
cross-section.
Aspect 17 of this disclosure pertains to the process of Aspect 15
or Aspect 16, wherein the clip further comprises an abutment edge
adapted at one end of the open-ended cross-section, the abutment
edge adapted to contact an edge surface of the first sheet of glass
material.
Aspect 18 of this disclosure pertains to the process of any one of
Aspects 14-17, wherein the clip has a length of from 5 mm to 50
mm.
Aspect 19 of this disclosure pertains to the process of any one of
Aspects 8 to 13, wherein the force is applied via a hanging weight
structure.
Aspect 20 of this disclosure pertains to the process of Aspect 19,
wherein the hanging weight structure comprises: a suspension body;
an overhang projection that extends from a first end of the
suspension body over the second outer surface of the second sheet
of glass material; an armature extending from a second end of the
suspension body, wherein a weight is suspended from the armature;
and a contact surface attached to the underside of the overhang
protection, wherein the contact surface contacts the second outer
surface of the second sheet of glass material.
Aspect 21 of this disclosure pertains to the process of Aspect 20,
wherein the contact surface comprises a flexible strip having a
V-shaped cross-section, wherein a bottom of the V-shaped
cross-section contacts the second outer surface.
Aspect 22 of this disclosure pertains to the process of any of
Aspects 8 to 13, wherein the force is applied via one or more
counterweights arranged at or near the edges and/or corners of the
first and second sheets of glass material.
Aspect 23 of this disclosure pertains to the process of any of
Aspects 8 to 13, wherein the force is applied via a press that is
lowered onto the second outer surface of the second sheet of glass
material.
Aspect 24 of this disclosure pertains to the process of any of
Aspects 8 to 13, wherein the force is applied via a flexible
weight.
Aspect 25 of this disclosure pertains to the process of Aspect 24,
wherein the flexible weight comprises a metal cable.
Aspect 26 of this disclosure pertains to the process of Aspect 25,
wherein the metal cable comprises at least one of copper, stainless
steel, nickel, a ceramic, or silver.
Aspect 27 of this disclosure pertains to the process of Aspect 24,
wherein the flexible weight comprises a braided metal fabric.
Aspect 28 of this disclosure pertains to the process of Aspect 27,
wherein the braided metal fabric is arranged as a hose, a tube, or
a sleeve.
Aspect 29 of this disclosure pertains to the process of any of
Aspects 24 to 28, wherein the flexible weight is connected to a
mounting ring via at least two cables.
Aspect 30 of this disclosure pertains to the process of Aspect 29,
wherein the mounting ring is connected to the shaping frame.
Aspect 31 of this disclosure pertains to the process of any of
Aspects 24 to 30, wherein the flexible weight causes no optical
distortions during the process.
Aspect 32 of this disclosure pertains to the process of any of
Aspects 24 to 31, wherein a fabric or layer comprising at least one
of copper, stainless steel, nickel, a ceramic, or silver is
provided between the flexible weight and the first glass sheet and
the second glass sheet.
Aspect 33 of this disclosure pertains to the process of any of the
preceding Aspects 1 to 32, wherein a layer of separation material
separates the first sheet of glass material from the second sheet
of glass material.
Aspect 34 of this disclosure pertains to the process of any of the
preceding Aspects 1 to 33, wherein the first sheet of glass
material has a first composition with a first viscosity during
heating that is different than a second viscosity of the second
sheet of glass material during heating, the second sheet of glass
material having a second glass composition.
Aspect 35 of this disclosure pertains to the process of any of the
preceding Aspects 1 to 34, wherein the first glass composition is
soda lime glass and the second glass composition is an alkali
aluminosilicate glass composition or an alkali aluminoborosilicate
glass composition.
Aspect 36 of this disclosure pertains to the process of any of the
preceding Aspects 1 to 35, wherein the first sheet of glass
material has an average thickness, T1, and the second sheet of
glass material has an average thickness, T2, wherein T1 is
different than T2.
Aspect 37 of this disclosure pertains to the process of Aspect 36,
wherein T1 is at least 2.5 times greater than T2 or T2 is at least
2.5 times greater than T1.
Aspect 38 of this disclosure pertains to the process of Aspect 36,
wherein T1 is between 1.5 mm and 4 mm, and T2 is between 0.3 mm and
1 mm.
Aspect 39 of this disclosure pertains to the process of any of the
preceding Aspects 1 to 38, wherein, after the heating step, the
first inner surface of the first sheet of glass material and the
second inner surface of the second sheet of glass material are
separated by no more than 0.5 mm at any point over the extent of
the first and second inner surfaces.
Aspect 40 of this disclosure pertains to a curved glass laminate
article, comprising: the first sheet of glass material and the
second sheet of glass material co-formed according to the process
of any one of Aspects 1 to 39; and a polymer interlayer binding the
first sheet of glass material to the second sheet of glass
material.
Aspect 41 of this disclosure pertains to a method of forming a
glass laminate article, the method comprising the steps of: placing
a first sheet of glass material on a support surface of a shaping
frame, the shaping frame defining an open central cavity surrounded
at least in part by the support surface; placing a second sheet of
glass material over the first sheet of glass material, wherein the
first sheet of glass material and the second sheet of glass
material are both supported by the shaping frame; heating the first
sheet of glass material and the second sheet of glass material
together while supported by the shaping frame such that central
regions of the first and second sheets of glass material deform
downward into the open central cavity of the shaping frame and the
first and second sheets of glass material are co-formed to have
similar curvatures; controlling a pressure in a space between the
first sheet of glass material and the second sheet of glass
material during at least a portion of the heating; and bonding the
first sheet of glass material to the second sheet of glass
material.
Aspect 42 of this disclosure pertains to the method of Aspect 41,
wherein controlling the pressure in the space further comprises
creating a low pressure region at or near one or more of the edges
and/or corners of the first and second sheets of glass
material.
Aspect 43 of this disclosure pertains to the method of Aspect 41,
wherein controlling the pressure in the space further comprises
applying a force at or near one or more edges and/or corners of the
first sheet of glass material and of the second sheet of glass
material to prevent an influx of fluid into the space.
Aspect 44 of this disclosure pertains to the method of Aspect 41,
wherein the force is from 0.1 N to 1 N.
Aspect 45 of this disclosure pertains to the method of Aspect 43 or
Aspect 44, wherein the force is applied over a distance of 6
mm.
Aspect 46 of this disclosure pertains to the method of any one of
Aspects 43 to 45, wherein the force is applied within 20 mm of an
edge of the first and second sheets of glass material.
Aspect 47 of this disclosure pertains to the method of any one of
Aspects 43 to 46, wherein the force is applied via one or more
clips, one or more hanging weight structures, one or more
counterweights, a press that is lowered on to an upper surface of
the second sheet of glass material, or a flexible weight.
Aspect 48 of this disclosure pertains to the method of any of
Aspects 41 to 47, wherein the first sheet of glass material has a
first glass composition that is soda lime glass and the second
sheet of glass material has a second glass composition that is an
alkali aluminosilicate glass composition or an alkali
aluminoborosilicate glass composition.
Aspect 49 of this disclosure pertains to the method of any of
Aspects 41 to 48, wherein bonding the first sheet of glass material
to the second sheet of glass material further comprises depositing
a polymer interlayer between the first sheet of glass material and
the second sheet of glass material.
Unless otherwise expressly stated, it is in no way intended that
any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its steps
or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is in no way intended that any particular order be inferred. In
addition, as used herein, the article "a" is intended to include
one or more than one component or element, and is not intended to
be construed as meaning only one.
It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the disclosed embodiments. Since modifications,
combinations, sub-combinations and variations of the disclosed
embodiments incorporating the spirit and substance of the
embodiments may occur to persons skilled in the art, the disclosed
embodiments should be construed to include everything within the
scope of the appended claims and their equivalents.
* * * * *